Generally, aerosol vessels indicate vessels that are filled with a substance (liquid or gas) to be sprayed and a propelling agent or propellant gas and hermetically sealed so that the substance can be sprayed using the pressure of the spray gas. Here, gas such as liquefied petroleum gas (LPG), dimethyl ether (DME), Freon, carbon dioxide, nitrogen, or oxygen is used as a propellant gas. A portable gas vessel, a mosquito sprayer, a hair sprayer, and a portable aerosol fire-extinguisher are representative aerosol vessels.
Since aerosol vessels, such as a portable gas vessel, a mosquito sprayer, a hair sprayer, and a portable aerosol fire-extinguisher, are filled with gas for ejecting contents, they are in danger of deforming or exploding when a pressure exceeding a predetermined value occurs in them.
As an example of an aerosol vessel, a portable gas vessel 10 shown in FIGS. 1 and 2 includes a main body 12 which has a cylindrical shape and receives gas therein; a top sealing cap 14 and a bottom sealing cap 14a which are integrally seamed to the top and bottom, respectively, of the main body 12 in order to hermetically seal the main body 12; a support member 20 which is compressively clamped at the center of the top sealing cap 14; and a nozzle assembly 30 which is installed at the support member 20 in order to eject gas stored within the main body 12. Hereinafter, a part including the support member 20 and the nozzle assembly 30 is defined as an aerosol valve assembly.
The nozzle assembly 30 includes a nozzle body 32 which is coupled with the support member 20 through the center of the support member 20 and is supported by the support member 20. The nozzle body 32 includes a predetermined space 32a, an opening at its top, and a gas inflow passage 32b at its lower portion. A valve stem 34 is installed such that it pierces through the center of the support member 20 and can move up and down within the upper portion of the nozzle body 32. The valve stem 34 includes a gas inlet 34a, through which gas stored in the main body 12 flows into the valve stem 34, and a gas ejection passage 34b, through which gas flowing in through the gas inlet 34a is ejected to the outside. An opening/closing ring 36 for opening or closing the gas inlet 34a of the valve stem 34 is installed at a portion where the support member 20 is coupled with the nozzle body 32. A support spring 38 for providing elasticity for an up-and-down motion of the valve system 34 is installed within the lower portion of the nozzle body 32.
In such a structure, during a normal use, when the valve stem 34 is pressed down into the main body 12 by an external force, the gas inlet 34a is opened due to the elastic transformation of the opening/closing ring 36, as shown in FIG. 2. Accordingly, gas within the main body 12 flows into the valve stem 34 through the gas inlet 34a and is ejected to the outside or a predetermined burner through the gas ejection passage 34b. 
However, in a conventional aerosol vessel such as the portable gas vessel 10 shown in FIGS. 1 and 2, propellant gas stored in the aerosol vessel may easily expand or explode when a shock or heat is externally applied to the aerosol vessel. The explosion of an aerosol vessel may cause a fire and injury to human life.
In order to delay or prevent the explosion of an aerosol vessel, a top sealing cap and a bottom sealing cap are regulated to have a fold and a curve so that an extra space can be secured taking into account the expansion of propellant gas stored in the aerosol vessel. However, if the propellant gas continuously expands even after the top sealing cap and the bottom sealing cap are flattened or swollen making the inner volume of the aerosol vessel maximum, a portion where the top sealing cap or the bottom sealing cap is seamed to the main body of the aerosol vessel is unseamed, so the aerosol vessel explodes.
Another approach for preventing the deformation and explosion of an aerosol vessel by discharging gas from the aerosol vessel before the inner pressure of the aerosol vessel increases and reaches a deforming pressure is disclosed in Korean Utility Model Publication No. 99-3911 (published on Jan. 25, 1999), entitled “Pressure Vessel with Residual Gas Discharge Device”. In this approach, a vessel includes a valve room with an inlet piercing through the side of the body of a valve assembly in a horizontal direction and a pressure application hole piercing through the bottom of the body of the valve assembly, a nozzle which is coupled with the upper portion of the valve room and forms a discharge passage communicating the valve room therebelow, and a plate valve which is received in the valve room such that it is elastically dropped down to be opened. According to the above structure, when the inner pressure of the vessel reaches a level at which contents cannot be discharged properly, the plate valve is opened making the inside of the vessel communicate with the outside, so residual gas can be discharged.